JPS60140945A - System for eliminating and controlling differently polarized signal - Google Patents

Abstract

PURPOSE:To decrease the interference due to differently polarized wave automatically by adjusting the amplitude and phase of a differently polarized signal, the synthesizing the adjusted differently polarized signal and a main polarized signal and extracting the differently polarized signal from the said synthesis signal so as to minimize the level thereby controlling the said adjusting means. CONSTITUTION:A horizontally polarized wave H component is fed directly to a synthesizer 4 and a vertical polarized wave V component is applied to the synthesizer 4 via a variable attenuator 2 and a variable phase shifter 3. In this case, the reception signal of the polarized wave H is used as the main polarized wave signal and the reception signal of the polarized wave V becomes the differently polarized wave signal. Thus, the level and phase of the polarized signal component of an adjacent channel are adjusted by a variable attenuator 2 and a variable phase shifter 3, and the attenuation of the variable attenuator 2 and the phase shift of the variable phase shifter 3 are controlled automatically by a control circuit 6 so as to minimize the level of the vertical polarized signal component extracted by a BPF5. Thus, even if the reception level of the main polarized wave signal is decreased, the interference by the differently polarized signal is reduced. When the differently polarized signal exists at both sides, the constitution shown in one dash chain lines is added.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention eliminates different polarization signals that interfere with a main polarization signal in a wireless communication system that performs communication using a plurality of polarization signals. This invention relates to a different polarization signal removal control method.

Prior Art and Problems In wireless communication systems, systems using a plurality of polarized signals are adopted due to the difference in frequency allocation. For example, a method in which the transmission frequency and the reception frequency are the same polarization frequency and a method in which different polarization frequencies are known are known, and the latter method is called an incremental method. Furthermore, as shown in FIG. 1, a method is known in which transmission and reception use different polarizations and frequencies. That is, with frequency f as the horizontal axis, channels CHI, CH2,
CH3+..., CHI', CH2', CH3
', . Transmission T, horizontal polarization H channel CH2' is reception R, and vertical polarization V channel CH3' adjacent to that channel is reception R1 horizontal polarization H channel CH3.
If the interval between these frequencies is narrow, transmission/reception multiplication interference where the transmitted signal wraps around the received signal and interference due to reception of signals with different polarization frequencies become a problem.

Figure 2 shows the main parts of the transmitter/receiver (2) that communicates using multiple polarized signals, and the transmitters THI, TH2, TH3, etc. that transmit using horizontally polarized waves H. ·and,
Transmitter TV that transmits using vertically polarized wave V 1. TV2.
TV3. ... means the circulator CIR, respectively.
receiving sections RH, RH2, RH3, . RV3
．． ” and are each coupled to the receiving antenna ANT2 via a circulator CIR.

For example, the vertically polarized transmission signal Tv of channel CH, in FIG. 1 is sent out from the transmitting antenna ANT1 in FIG. There is interference due to leakage as shown in Rv shown in Fig. 1. This is called antenna side-to-side interference (SS interference). , if the receiving frequencies of different polarizations are adjacent, the receiving antenna ANT2
, a received signal Rh of horizontal polarization H and a received signal Rv' of a certain vertical polarization (3) with different polarization are received, and this received signal Rv' interferes with the received signal Rh.
This will cause PD interference.

The aforementioned SS interference and XPD interference can be alleviated by narrowing the transmission spectrum or the filter band in the receiving section, but narrowing the filter bandwidth will result in a reduction in transmission power. Transmission characteristics such as amplitude characteristics and delay characteristics deteriorate. Therefore, it was not possible to narrow the band of the filter. Therefore, when the frequency interval is narrow, interference cannot be reduced. Also, transmitting antenna ANT1 and receiving antenna ANT2
It is possible to reduce the SS interference by changing the arrangement relationship between the antennas and the antennas, or to reduce the XPD interference by antennas between transmitting and receiving antennas during spatial propagation, but there are limits both physically and methodically. In particular, when a 64QAM (64-value quadrature amplitude modulation) method is adopted, the spectrum spreads, so the SS interference will be about 20 to 30 dB, and the XPD interference will be about 20 dB.

If SS interference and XPD interference are large as described above, (4) it becomes difficult to set up an actual wireless line with a narrow frequency interval.

Purpose of the Invention The present invention provides an S
The purpose is to reduce S interference and XPD interference.

Structure of the Invention The present invention provides an adjustment means for adjusting the amplitude and phase of a different polarization signal that interferes with a main polarization signal in a wireless communication system that performs communication using a plurality of polarization signals; a synthesizing means for synthesizing the different polarization signal adjusted by the adjusting means and the main polarization signal; extracting the different polarization signal from the signal synthesized by the synthesizing means; The adjustment means is controlled so that the level is minimized,
It is possible to automatically reduce interference due to different polarizations. Examples will be described in detail below.

Embodiment of the Invention FIG. 3 is a block diagram of the main parts of an embodiment of the present invention (5), where ■ is a receiving antenna, 2 is a variable attenuator, 3 is a variable phase shifter, 4 is a combiner, and 5 is a A bandpass filter, 6 is a control circuit. Also, 2゛, 3'' within the dashed line.

5" and 6" are variable attenuators, variable phase shifters, bandpass filters,
It is a control circuit. Horizontal polarization H received by receiving antenna 1
The component is directly added to the combiner 4, and the vertically polarized wave component is added to the combiner 4 via the variable attenuator 2 and the variable phase shifter 3. In this case, the received signal of horizontal polarization H is the main polarization signal, and the reception signal of vertical polarization (2) is a different polarization signal.

The bandpass filter 5 has a band for extracting a different polarization signal, and the control circuit 6 controls the variable attenuator 2 and the variable phase shifter 3 so that the level of the signal extracted by the bandpass filter 5 is minimized. It outputs a control signal to control the

In Fig. 4 fa), if the frequency interval of channels (1) and +21 is narrow as shown by Δf, the received signals of the same polarization of each channel (11 and (21) are shown with diagonal lines. This overlap will cause interference.This overlap can be eliminated to some extent by using a narrowband filter (6), but as mentioned above, the transmission characteristics There is a limit to narrowing the filter band because this will cause deterioration of the filter.Furthermore, if vertically polarized waves are received with a horizontally polarized antenna, the received power of the vertically polarized signal will be approximately lower than that of the horizontally polarized signal. 20dB
to a lesser extent.

That is, as shown in (b), the horizontally polarized wave H channel (
The vertically polarized signal component of the adjacent channel (2) is about 20 dB lower than the received signal power of (1). On the contrary, as shown in C1, the horizontally polarized signal component of the adjacent channel (1) is about 20 dB lower than the received signal power of the channel (2) of the vertically polarized wave V.

As mentioned above, with respect to the horizontally polarized signal of channel (1), the vertically polarized signal component of the adjacent channel (2) has an overlapping portion shown by diagonal lines in (bl) in Fig. 4. The interference can be eliminated by removing this shaded part.Therefore, by adjusting the level and phase of the vertically polarized signal of channel (2), (7) This is to cancel the vertically polarized signal component contained in the horizontally polarized signal.For example, the reception level of the vertically polarized signal of channel (2) shown in (C1) is attenuated by about 20 dBM to By inverting its phase by 180 degrees and combining it with the received signal of channel (1) shown in (b), the vertically polarized signal component can be canceled out.In that case, (
As shown in dl, since the horizontally polarized signal component of the main signal is also included, it will affect the main signal, but the degree of influence is very small, and the vertically polarized signal of the adjacent channel (2) The effect of canceling the interference caused by the components is large, and the influence on the main signal is negligible.

The level and phase of the polarized signal components of adjacent channels as described above are adjusted by the variable attenuator 2 and variable phase shifter 3 shown in FIG. The attenuation amount of the variable attenuator 2 and the phase shift amount of the variable phase shifter 3 are automatically controlled so as to minimize the level of the vertically polarized signal component.
Even in the case where the reception level of the main polarization signal decreases due to fading (8), the interference caused by the different polarization signal can be reduced as described above.

In addition, if different polarization signals exist on both sides of the polarized signal as the main signal and cause interference, the configuration shown by the dashed line is added, and the interference frequency signals on both sides of the main signal are filtered using bandpass filters 5, 5. The components are extracted and the variable attenuator 2.2' and variable phase shifter 3.3' are controlled so that the respective levels are minimized.

Although the above embodiment shows the case where the main signal is horizontal polarization, it can be similarly applied to the case where the main signal is vertical polarization. The amount of attenuation and the amount of phase shift are adjusted and combined with the vertically polarized signal of the main signal, thereby canceling out the horizontally polarized signal component included in the vertically polarized signal of the main signal.

DETAILED DESCRIPTION OF THE INVENTION As described above, the present invention provides a variable method (9) for adjusting the amplitude and phase of a different polarization signal such as a vertically polarized signal that interferes with a main polarized signal such as a horizontally polarized signal. The combining means includes adjusting means such as an attenuator 2 and a variable phase shifter 3, and combining means such as a combiner 4 that combines the different polarization signal adjusted by the adjusting means and the main polarization signal. The different polarization signals are filtered from the signals synthesized by the bandpass filter 5.
etc., and the adjusting means is controlled so that the level of the different polarization signal is minimized.As a result, the interfering different polarization signal that causes interference can be canceled out, so the frequency interval with the adjacent channel can be reduced. There is an advantage that even when the polarization is narrow, interference due to different polarization signals can be easily reduced. Therefore, SS interference and XPD interference can be reduced without deteriorating transmission characteristics by keeping the filter band the same as before.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram of the arrangement of transmitting and receiving channels using horizontally polarized waves H and vertically polarized waves ■, Figure 2 is a block diagram of the main parts of a transmitting and receiving device using multiple polarized signals, and Figure 3 is the invention of the present invention. FIG. 4 (8) to (dl) are explanatory diagrams of interference and interference cancellation. (10) ANTI is a transmitting antenna, ANT2 is a receiving antenna, and T
H,, TH2, TH3,..., TVI, TV2. TV
3. ” ' is the transmitter, RH,, RH2, RH3,...+
, Rv, , RV2+ RV3,... is the receiving section, CIR
is a circulator, 1 is a receiving antenna, 2 is a variable attenuator, 3 is a variable phase shifter, 4 is a combiner, 5 is a bandpass filter, 6
is the control circuit. Patent applicant: Fujitsu Ltd. Representative Patent Attorney: Shoji Aitani Representative Patent Attorney: Hiroshi Watanabe - (11) Figure 3 H 23H5: ■ ■ 17;' 2 -%-1 ~ 1 1 1 Li-1; 1 1 6 (b) (C) (li (2) 241- (d)

Claims (1)

[Claims] In a wireless communication system that performs communication using a plurality of polarized signals, there is provided an adjustment means for adjusting the amplitude and phase of a different polarization signal that interferes with a main polarization signal; a combining means for combining a different polarization signal and the main polarization signal, extracting the different polarization signal from the signal synthesized by the combining means, and extracting the different polarization signal so that the level of the different polarization signal is minimized. A different polarization signal removal control method, characterized in that the adjustment means is controlled.